HF-275 Helios

25 years jubileum project from the danish High Fidelity magazine

Helios is the updated revision designed by Niels Nørby and Roland Sørensen.

Might just be the most rewarding DIY project I've ever done. My first and partially successful attempt to glue wood veneer.

So called 2 1/2 way speaker with the low bass tapped from the 2 way crossover with a big 22uF inductor in series.

Some users later started to experiment with much simpler filter circuits and preferred the less accurate but more open sound from 6 and 12 dB filters.

Had a couple mishaps with DIY amps with no serial caps in the signal path resulting in a burned out tweeter and later a (sub)bass elements due to oscillation and DC offset over the 15 years we had this setup running. Call from home saying there are high pitched sound and smoke coming from one of the speakers makes your heart rate take that's days exercise.

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HF-275_Helios.pdf
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crossover.png
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inductor.png
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Delightful HF-275 Helios.jpg
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HF-275_Helios_Delefilter_01.JPG
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hf275_front.jpg
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speakerwindings.jpg
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